Biomedical subjects

L Vasileva

Publications and source records attributed to L Vasileva.

At least 19 recordsLinked to original sources

PubMed1986

[Demonstration of ligands for antibodies against the M protein on the virion surface of the Newcastle disease virus (NDV)].

Demonstrated was the presence of ligands for antibodies to the M-protein on the surface of NDV virions, using the hemagglutination-inhibition reaction, the immunodiffusion test in agar gel, the indirect variant of the enzyme-linked immunosorbent assay, and the immunosorbent micromethod with nitrocellulose membranes. Data spoke of transmembrane interactions between the M-protein and the glycoproteins of the envelope, which was of basic importance with regard to the biologic role played by this essential structural virus protein. The presence of ligands made it reasonable to believe that the M-protein played a part in the building up of antiviral immunity.

Animals↗

PubMed1986

[Demonstration of the M-protein of the Newcastle disease virus by current immunochemical methods].

The immunosorbent micromethod with the use of nitrocellulose paper was employed for the first time to demonstrate subviral antigens from animal origin, such as the M-protein of the Newcastle Disease virus. The method proved to be highly effective. It was useful in discovering amounts as high as 10-20 ng of the antigen, while with the use of the enzyme-linked immunosorbent assay (ELISA) amounts of about 200 ng could be evaluated. The immunosorbent micromethod performed on nitrocellulose paper was readily applicable as compared to all previously employed highly sensitive methods, and could be used successfully in immunochemical investigations.

Animals↗

PubMed1986

[Antigenic properties of NDV glycoproteins synthesized in the presence of 2-deoxy-d-glucose].

Experiments were carried out to establish whether the glucose antimetabolite, 2-desoxi-d-glucose (DDG), effected the proteolytic breakdown of the envelope proteins of NDV and if there was any effect on there antigenic properties. It was found that it inhibited the glucose action on the NDV envelope proteins, the hemagglutinin-neuraminidase (HN), and the F-protein so that their biologic properties were not manifested, and the production of infectious virus was blocked. In the presence of DDG the virus-infected were shown to contain the virus envelope proteins, the membrane protein, and the nucleocapsid both through electrophoresis in 10 percent polyacrylamide gel and through the agar gel immunodiffusion test (with the use of specific rabbit anti-HN, anti-F protein, and anti-M protein sera). The antigenic properties of the two glycoproteins of the NDV envelope did not change under the action of the DDG inhibitor as seen by the precipitation lines of the control variants (cells infected with the virus but not treated with the antimetabolite), which were identical with those obtained with the test variants (cells treated with DDG).

Animals↗

PubMed1986

[Membrane protein formation in cells infected with the NDV virus and treated with theophylline].

The effect of theophylline on the synthesis of NDV membrane protein which plays an essential role in the production of virions was followed up. It was found that the replication of the virus in chick embryo fibroblasts was inhibited when the cells were treated with 1 mM theophylline. Inhibition was found to concern the final phase of virus replication--the formation of mature infection particles. The amount of membrane protein responsible for virus budding was analogous to that in the cells untreated with theophylline. It is believed that theophylline treatment of cells affects somehow the synthesis of viral proteins and changes their conformation.

Animals↗

PubMed1986

[Isolation of the glycoproteins of the Newcastle disease virus (NDV)].

Two NDV glycoproteins--hemagglutinin-neuraminidase and F-protein--were separated from the remaining structural virus proteins through treatment of the virions with a 2 per cent triton-x-100 and chromatography on a Koh A-sepharose 4B column. A subsidiary ion-exchange chromatography on DEAE--Sephadex technique was employed to separate the two products and obtain them in a pure state. Biologically active NDV glycoproteins were obtained through solubilization of the virions with 10 per cent triton-x-100 at high ion strength, and the two glycoproteins were separated on a DEAE-bio gel column with the use of 0.01 M phosphate buffer of pH 7.2, containing 0.5 M NaCl.

Chromatography, Affinity↗

PubMed1985

[Development of a method for the quantitative determination of the immunizing antigen (140S) of the foot-and-mouth disease virus].

Attempts were made to work out a method for measuring the amount of the 140 S antigen in virus suspensions. Early postinfection sera were obtained from guinea pigs against the productional strains of the foot-and-mouth disease virus which were used in the radial immunodiffusion test. The investigated virus suspensions were concentrated 50 to 200 times and were placed in a CsCl gradient for gradient centrifugation. The 140 S antigen fractions obtained were titrated in a radial immunodiffusion test. The size of the resulting precipitation circles were defined for the individual dilutions of the antigen, and the method of least squares was employed to establish the standard straight lines for each of the investigated productional strains of the FMD virus. The new method makes it possible to fix the content of the 140 S antigen in productional series of the FMD virus intended for vaccine production.

Animals↗

PubMed1985

[Experiments to purify and concentrate the foot-and-mouth disease virus].

Experiments were carried out for the purification and concentration of the foot-and-mouth disease virus. For the purpose the virus suspensions were treated with chloroform and 8 per cent polyethylene glycol. The precipitated virus was eluated with phosphate buffer (of pH 7.6) up to 1:100 of the initial volume. The concentrated virus was subjected to gradient ultracentrifugation on gradient of CsCl. The fractions obtained were investigated through radial immunodiffusion reaction with early sera, containing IgM antibodies. The fractions that formed circles of precipitation were studied under electron microscope at negative contrasting. It was found that the fractions taken from between the CsCl layer of 1.42 g/cm3 density and the underlying CsCl layer of 1.50 g/cm3 density, which produced precipitation circles in the radial immunodiffusion test, contained purified virions of intact structure in concentration of 10(9).

Animals↗

PubMed1985

[Biochemical changes in the myocardium in experimental chronic pirazofos poisoning].

The authors investigate the 12 month effect of the organophosphorus pesticide "Pyrazophos", in the myocardium status of albino male rats treated per os by 1/20, 1/100, and 1/200 LD50 of the preparation /LD50 for male rats 218 mg/kg/. The enzyme activity of ATP-ase, G6P-ase, F1,6 P-ase, PGlM, LDH, SucDH, iCDH, the quantity of soluble and insoluble collagen and elastin proteins were examined as well as the content of polycarbohydrate components /total and sulphated glycosaminoglycan and glycoproteins/ of the basic intercellular substance. The results point out that the preparation in doses 1.1 and 2.2 mg/kg and especially 11 mg/kg at continuous introduction cause cardiotoxic effect, and the changes affect first of all the components of the basic intercellular substance /with sGAG, GAG/ and to a lighter extent the enzyme activity in the cardiac muscle. The collagen and elastin proteins, constructing the fibrous structures remain comparatively stable. The experimental data have to be taken into consideration in the hygiene standardization of the organophosphorus preparation "Pyrazophos".

Animals↗

PubMed1985

[Inhibition of NDV replication by theophylline].

Theophylline is said to produce an inhibiting effect on the replication of the Newcastle disease virus in chick embryo fibroblast cultures when used in conc. of 1 mM. When the cultures are treated with theophylline 24 hours prior to their infection or following one-hour adsorption the virus titer is lowered in the process of replication by about 2 lg as against the titer when the virus is replicated in theophylline-free cultures. The inhibiting effect consists in blocking or arresting the production of mature virions.

Adsorption↗

PubMed1984

[Demonstration of envelope-containing viruses by the agglutination of antibody-coated Staphylococcus aureus].

A rapid agglutination method was worked out for the demonstration of the Newcastle disease virus (NDV) and the bovine leukosis virus (BLV) with the use of specific antibody-charged Staphylococcus aureus cells. It consists in the production of formalin-treated St. aureus cells, their sensibilization with specific antibodies, and their agglutination with the respective viral antigens. The latter were obtained from cell lines infected with NDV, resp., BLV as well as with purified NDV. It is concluded on the basis of the results obtained that the agglutination test suggested is rapid, specific, and sensitive and can be employed as an adjunct means in various immunochemical investigations and in the practice for the demonstration of the virus in infectious material.

Agglutination Tests↗

PubMed1984

[Isolation of the Fab fragment from immune sera].

A Fab-fragment was obtained from rabbit anti-swine JgG serum through the breakdown of JgG by means of the proteolytic enzyme pepsin in ion-exchange chromatography on DEAE cellulose. It was found that the Fab-fragment gave no positive precipitation in the immunodiffusion agar gel test, and in electrophoresis on 10 per cent acrylamide gel following preliminary breakdown with 1 per cent SDS and 2 per cent ME and heat treatment at 100 degrees C for 2 minutes it showed only one polypeptid chain with equal mobility as that of the light JgG chain. On the basis of the results obtained speculations are made of the mode and site where pepsin supposedly acts.

Animals↗

PubMed1984

[Restoration of the biological activity of hemagglutinin--neuraminidase in NDV with phospholipids].

The phospholipids in the membrane of the Newcastle disease virus were hydrolysed by means of the phospholipase enzyme C, whereas the infectious titer of the virus did not change, however its neuraminidase activity dropped. It was found that sphingomyelin in conc. of 250 micrograms/cm3 or lipids of the Newcastle disease virus membrane added to phospholipase C-treated hemagglutinin-neuraminidase restored its activity. The phospholipid 'phosphatidiletanolamine' could not restore the activity of the virus neuraminidase.

HN Protein↗

PubMed1983

[Inhibition of NDV reproduction with antibodies against its F protein].

Obtained were the JgG and Fab fragments from a monovalent serum against the F-protein of the Newcastle disease virus. Both the JgG and the Fab fragment inhibited the virus reproduction in cell cultures of chick embryo fibroblasts and BHK21 if they were added after the adsorption and virus penetration of the cells. The inhibitory action of the antibodies was due to their direct fixation by the newly synthesized F-protein in the cells infected with the virus. The rate of inhibition of the Newcastle disease virus as shown by the JgG and Fab fragments of the serum produced against a pure F-protein was the same with the use of chick embryo fibroblasts as with BHK21.

Adsorption↗

PubMed1982

[Demonstration of Newcastle disease virus by enzyme-linked immunosorbent assay].

Investigations were carried out with regard to the application of the sensitive, rapid, and effective enzyme-linked immunosorbent assay (ELISA) in the demonstration of the Newcastle disease virus (NDV). Used was the peroxydase-marked immunoglobulin fraction of the anti-DV rabbit serum in the microconditions of the double-antibody method. The demonstration of the NDV was in a cultivation liquid of NDV-infected BHK21 cells. As control served intact cells as well as strains Roussev and La Sota of NDV pruified through ultracentrifugation on an isokinetic saccharose gradiend. It is stated that ELISA is much more sensitive than the hemagglutination test and the agar gel immunodiffusion test.

Animals↗

PubMed1981

[Use of cell agglutination with concanavalin A to detect cattle infected with the leukemia virus].

The method of cell agglutination with concanavalin 'A' was employed to study lymphocytes from the peripheral blood of cattle spontaneously infected with the virus of leukosis. The infection in the animals was demonstrated through the agar gel immunodiffusion test based on the presence of antibodies. As controls served lymphocytes of normal cattle that were serologically and clinically negative for leukosis as well as lymphocytes, of cattle that were immunized with the virus of the mucous disease and with adeno-, rota, and parainfluenza-3 viruses. It was found that 10(6) lymphocytes of cattle infected with the leukosis virus was agglutinated by concanavalin 'A' used at the rate of 500-2000 microgram/cm3, while the same amount of lymphocytes of normal animals or animals that were immunized against the other viruses got agglutinated by concanavalin 'A' at 4000-8000 g/cm3.

Agglutination Tests↗

PubMed1981

[Antigenic differences in the glycoproteins of the Newcastle disease virus].

The two glucoproteins of the Newcastle disease virus - hemagglutinin-neuraminidase (HN) and F-protein - were isolated in a pure state from two strains of the virus: the La Sota apathogenic strain and the Roussev strain pathogenic for birds. It was found that the large HN glucoprotein of each of the strains was not identical antigenically with the F-protein. These seemed to be partial antigenic relatedness between the HN of the two strains. On the other hand, the F-proteins of the strains were identical.

Antigens, Viral↗

PubMed1980

[Comparative studies of sera from cattle with complete leukemia virus and glycoprotein antigens].

One hundred cattle serums were investigated by the AGTD-test with two antigens: an antigen produced by the whole virus and an antigen containing glycoproteins. Of all serums studied 44 showed a specific precipitation in case the glycoprotein antigen was used. In case the antigen from the whole virus was used 41 serums showed a specific precipitation line, while in 3 of the serums two precipitation lines were observed. Fifty six serums proved negative, containing no antibodies against bovine leucosis virus, after antigens were used. In 2 of the serums non specific precipitation lines were obtained when the antigen from whole virus was used. the precipitation lines produced by both antigenes did not differ in intensity and time of manifestation.

Animals↗

PubMed1979

[Purification of coronaviruses from contaminated cattle feces].

A scheme was worked out for the obtaining of purified Corona viruses from fecal extracts, which include: centrifugation in an discontinued gradient of sucrose 20--45 per cent, gel filtration through a Sephadex 4B column, and centrifugation in a linear gradient of sucrose 10--50 per cent. By means of such purification the virions remain morphologically intact in sucrose density of 1.11--1.14 gr/cm3, containing no ballast proteins. As many as five polypeptides are demonstrated in polyacrylamide electrophoresis.

Animals↗